Expansion of e.g.f. x^2/(1-4*x).

Terms

a(0) =0a(1) =0a(2) =2a(3) =24a(4) =384a(5) =7680a(6) =184320a(7) =5160960a(8) =165150720a(9) =5945425920a(10) =237817036800